Purpose

To solve the shortcomings of existed search and rescue drones, search and rescue the trapped people trapped in earthquake ruins, underwater and avalanches quickly and accurately, this paper aims to propose a four-axis eight-rotor rescue unmanned aerial vehicle (UAV) which can carry a radar life detector. As the design of propeller is the key to the design of UAV, this paper mainly designs the propeller of the UAV at the present stage.

Design/methodology/approach

Based on the actual working conditions of UAVs, this paper preliminarily estimated the load of UAVs and the diameters of propellers and designed the main parameters of propellers according to the leaf element theory and momentum theory. Based on the low Reynolds number airfoil, this paper selected the airfoil with high lift drag ratio from the commonly used low Reynolds number airfoils. The chord length and twist angle of propeller blades were calculated according to the Wilson method and the maximum wind energy utilization coefficient and were optimized by the Asymptotic exponential function. The aerodynamic characteristics of the designed single propeller and coaxial propeller under different installation pitch angles and different installation distances were analyzed.

Findings

The results showed that the design of coaxial twin propellers can increase the load capacity by about 1.5 times without increasing the propeller diameter. When the installation distance between the two propellers was 8 cm and the tilt angle was 15° counterclockwise, the aerodynamic characteristics of the coaxial propeller were optimal.

Originality/value

The novelty of this work came from the conceptual design of the new rescue UAV and its numerical optimization using the Wilson method combined with the maximum wind energy utilization factor and the exponential function. The aerodynamic characteristics of the common shaft propeller were analyzed under different mounting angles and different mounting distances.

中文翻译：

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新型救援无人机螺旋桨设计及气动特性分析

目的

为解决现有搜救无人机的不足，快速、准确地搜救地震废墟、水下、雪崩等被困人员，本文旨在提出一种四轴八旋翼救援无人机，该无人机能够快速、准确地搜救被困人员。携带雷达生命探测器。由于螺旋桨的设计是无人机设计的关键，因此本文现阶段主要对无人机的螺旋桨进行设计。

设计/方法论/途径

根据无人机的实际工况，初步估算了无人机的载荷和螺旋桨直径，并根据叶元理论和动量理论设计了螺旋桨的主要参数。本文以低雷诺数翼型为基础，从常用的低雷诺数翼型中筛选出高升阻比的翼型。根据威尔逊法和最大风能利用系数计算螺旋桨叶片的弦长和扭转角，并通过渐近指数函数进行优化。分析了所设计的单桨和同轴桨在不同安装螺距角和不同安装距离下的气动特性。

发现

结果表明，同轴双桨设计在不增加螺旋桨直径的情况下，可将负载能力提高约1.5倍。当两螺旋桨安装距离为8 cm、逆时针倾斜角度为15°时，同轴螺旋桨的气动特性最佳。

原创性/价值

这项工作的新颖性来自于新型救援无人机的概念设计及其采用威尔逊方法结合最大风能利用率和指数函数的数值优化。分析了共轴螺旋桨在不同安装角度和不同安装距离下的气动特性。